A stepping motor has been applied to a variety of fields such as a floppy disk driver, a printer, a servomechanism, and the like. The stepping motor includes a shaft, a lead screw formed on a first end of the shaft, a magnet fixed on a second end of the shaft, and a stator applying electric field around the magnet. The shaft functions as a rotor cooperating with the stator. A transfer member is engaged with the lead screw. Accordingly, when the lead screw rotates, the transfer member reciprocates.
The operation of the stepping motor will be described hereinafter briefly. The shaft rotates by electromagnetic force generated between the magnet and the stator. When the shaft rotates, the lead screw rotates together with the shaft. At this point, the transfer member coupled to the lead screw moves in a direction of axis thereof.
Formed on opposite ends of the shaft are bearings supporting the shaft and preventing the shaft from being removed. The bearing has a complicated structure composed of balls, springs and guides.
In an assembling process of the stepping motor, the above-described parts are connected to each other. Therefore, after the assembling process is finished, there may be interference between the parts adjacent to the shaft, thereby deteriorating the rotational performance of the motor and reducing the service life of the motor.
Furthermore, the connection processes between the many parts makes it complicate to assemble the stepping motor, thereby deteriorating the working efficiency.